1. Field of the Invention
The present invention relates to a double base type double azimuth magnetic head which is attached to a rotary drum for use as a recording/reproducing head in a magnetic recording/reproducing apparatus such as a video tape recorder (VTR).
2. Description of the Prior Art
In an ordinary VTR, generally a magnetic head H is attached to a rotary drum D as illustrated in FIG. 16 and serves to record a signal on and/or to reproduce the same from a magnetic tape wound around the rotary drum D. Head chips 31 constituting the magnetic head are attached to a head base 32 in such a manner that, as illustrated in FIG. 17, the head chips 31 are positioned on a projection 33 at the fore end of the head base 32. And the head base 32 holding the head chips 31 thereon is secured to the rotary drum D by means of a screw 34.
In a VTR of another type designed to perform variable speed reproduction, as illustrated also in FIG. 17, two head chips 31 are attached to the projection 33 of the head base 32 so as to constitute a double azimuth head. Such magnetic head is similar to the known example disclosed in Japanese Utility Model Laid-open No. 60 (1985)-70916.
In assembling such conventional double azimuth head, first the two head chips 31 are anchored to the head base 32 and, after coils are wound around the two head chips 31 respectively, a test is carried out by measuring the output characteristics of the two head chips. Therefore it becomes necessary to wind coils respectively around the two head chips 31 which are in extreme proximity to each other, thereby rendering the winding operation difficult or requiring a long operation time with another disadvantage of inducing difficulty for automation. Furthermore, in case one of the head chips 31 is found defective as a result of such test, it follows that both head chips are compelled to be discarded to consequently bring about waste.
In addition to the above problems, there exists in the double azimuth head the necessity of minimizing the dimensional error within a predetermined precision range of several microns or so with regard to the difference d between the distances a and b from the upper surface of the head base 32 to the edges of the respective gaps g of the two head chips 31 shown in FIG. 18. However, in manufacture of the head chips 31, some variations on the order of .+-.10 microns are caused in the dimensional values of the distances a and b. Therefore the head chips 31 manufactured are dimensionally classified into ranks by the distances a and b to form selected pairs, and then a pair of such selected head chips are joined to the base 32. However, classifying the head chips into ranks necessitates another step for selection of adequate head chips to consequently bring about additional labor for assembly of the heads with another disadvantage of increased production cost.